1. Field of the Invention
This invention relates generally to a magnetic recording and/or reproducing apparatus such as a Video Tape Recorder (VTR) and, more particularly, is directed to an improved automatic tape loading and unloading device for such apparatus.
2. Description of the Prior Art
Existing video tape recording and reproducing apparatus generally comprise a tape guide drum having a rotary magnetic head assembly associated therewith to record or reproduce video signals on or from a magnetic tape which is usually wound on supply and take-up reels with the tape between such reels being wrapped about a portion of the circumferential surface of the drum and being driven by cooperation of capstan and pinch roller and by suitable rotation of the take-up reel. In preparing such a video tape recording and reproducing apparatus for operation, the tape extending between the supply and take-up reels must be placed around at least a portion of the drum circumference so that the tape will be guided thereby with respect to the rotary magnetic head assembly. Conventionally two types of automatic tape loading and unloading devices are used for video signal recording and/or reproducing apparatus.
One type of automatic tape loading and unloading device is called "U-type loading device" and is disclosed in U.S. Pat. No. 3,821,805 assigned to the same assignee as this application. As shown in this patent, the loading device is provided with a loading ring on which plural tape drawing guides are mounted which are inclined to the circumferential surface of a rotary head drum. The tape drawing guides are moved along the circumferential surface of the rotary head drum with the rotation of the loading ring. The tape is drawn from a tape cassette, and is wrapped on the rotary head drum substantially in a U-shape.
In the above-described tape loading and unloading device a pinch roller and a capstan for driving the tape are positioned between the tape exit of the rotary head drum and the tape drawing guide around which the tape turns. The fine tape vibration, which is apt to occur at the tape turning point where the tape wrap angle is large, is intercepted by the tape pinching point between the capstan and the pinch roller and, therefore, such vibration is prevented from being transmitted to the rotary head drum and the tape is smoothly transported. Guides for regulating tape transport at the tape exit and entrance of the rotary head drum can be fixed. Accordingly, the tape runs very smoothly and the adjustment of the tape path is relatively easy. Accuracies of guides of the like arranged in the tape downstream with respect to the pinching point between the capstan and pinch roller have little influence on tape transport. Accordingly, the positioning accuracy of the tape drawing guide for tape turning is not required to be high. As a result, the apparatus can be of simplified construction.
However, in the U-type loading apparatus the fixed guides for tape entrance and exit, the capstan, a sound/control head and an erasing head must be arranged within the loading ring. Accordingly, the outer diameter of the loading ring is very large. The area required for the whole tape loading apparatus must be increased in proportion to the outer diameter of the loading ring. Further, the loading ring is mounted on a chassis at such an angle to the horizontal surface that is about twice as large as the loading angle of the tape to the rotary head drum. Accordingly, the height of the whole tape loading apparatus becomes relatively large.
As above described, this U-type loading apparatus has the drawback that the whole apparatus is unnecessarily large in size.
The other automatic tape loading and unloading device, which is called M-type loading device, is disclosed in U.S. Pat. No. 4,122,506 issued Oct. 24, 1978. In this type loading device two sets of tape drawing guides are horizontally moved at both sides of a rotary head drum. The tape is horizontally drawn out from a tape cassette and is wrapped on the rotary head drum substantially in an M-shape. The capstan is vertically arranged on a horizontal chassis but the rotary head drum is inclined at an angle that is about twice as large as the loading angle of the tape to the rotary head drum. Thus, the height of the tape loading apparatus is little influenced by the tape loading ring. Accordingly, the height of the M-type loading device may be reduced to some extent.
However, in the M-type loading device the two sets of the tape drawing guides, after being moved to both sides of the rotary head drum, are fixed at the tape exit and entrance of the rotary head drum for regulating tape transport to the rotary head drum. With this arrangement it is difficult to position the tape drawing guides with a high degree of accuracy. Accordingly, it is difficult for the tape to run smoothly. Further, the construction for fixing the tape drawing guides is complicated resulting in a relatively higher cost of manufacture.
In addition, a slant guide for changing the path of the tape must be arranged between the tape pinching point of the capstan and pinch roller and the tape exit of the rotary head drum. The tape is wrapped on the slant guide over a considerably large extent and fine tape vibration is apt to be transmitted to the rotary head drum. To avoid the fine tape vibration an impedance roller is provided. However, this requires a more complicated construction.